1. Field of Invention
The present invention relates to a high performance liquid chromatograph with trap functions like condensing sample components and a flow path switching valve used by the high performance liquid chromatograph with trap functions.
2. Description of Related Art
Among quality analyzers used for determining the structures of protein or peptide in the life science field, in order to optimize the measurement sensitivity, those involved in the art make great effects to minimize the flow of the high performance liquid chromatograph (HPLC) at the previous stage.
Generally, HPLCs for ordinary analysis operate by transmitting mobile phase at a flow speed of about 1 mL/min in a chromatographic column with an inner diameter of 4.6 mm. However, as for quality analyzers, micrometer HPLCs that transmit liquid at a flow speed of about 5 μL/min in a chromatographic column with an inner diameter of about 0.3 mm are generally adopted. In addition, nanometer HPLCs that transmit mobile phase at a flow speed of about 200 nL/min in a chromatographic column with an inner diameter of 0.075 mm have been commercialized.
When those extremely low-flow HPLCs are used for analysis, the object for being analyzed may be diffused due to the volume of the system (about 100 μL), thus affecting the sensitivity of the quality analyzer. Therefore, an auto-sampler or a manual injector is used to inject the object to be analyzed into the system. Next, the object to be analyzed is absorbed in the trap column mounted on the temporary flow path switching valve for being condensed. Then, the flow path switching valve is switched to transmit the mobile phase used for analyzing into the trap column. Thereafter, the above object to be analyzed is removed from the trap column, and then analyzed via an analytical column. Finally, the quality of the above object is analyzed by a quality analyzer.
The flow path switching valve employed in an extremely low-flow HPLC has a small inner volume due to the same reason as mentioned above. Generally, the main components of a flow path switching valve include a housing top for fixing the pipes that are led into the flow path switching valve, a rotor for switching flow paths through rotation, and a stator for keeping liquid-tight between the housing top and the rotor. In addition, the housing top may also serve as a stator occasionally.
FIG. 4A˜4B show a conventional flow path switching valve. FIG. 4A is a general sectional view, and FIG. 4B is a general plan view.
The flow path switching valve 50 includes: a rotor for switching flow paths, i.e., rotor 53, a stator 55 contacting the rotor 53 to keep liquid-tight therebetween, and a housing top 59 for maintaining the stator 55 and having ports 51a-51f connected to external flow paths. The valve 50 is supported and driven by a valve supporting portion indicated by a dashed line. Among the ports 51a-51f, two ports used for the mobile phase for analyzing are an inlet port 51a and an outlet port 51b, another two ports used for the mobile phase for condensing are an inlet port 51c and an outlet port 51d, and the rest ports used for connecting the trap column 57 are ports 51e, 51f (referring to Japanese Patents Publication No. 01-307575, No. 09-288098).